1. Field of the Invention
The present invention relates to plasma processing apparatuses, plasma processing systems, and performance validation systems and performance inspection methods thereof. In particular, the present invention relates to a technology which is suitable for power supply of higher frequencies and achieves improvements in power consumption efficiency and coating layer characteristics.
2. Description of the Related Art
FIG. 32 illustrates a typical conventional dual-frequency excitation plasma processing apparatus which performs a plasma process such as a chemical vapor deposition (CVD) process, a sputtering process, a dry etching process, or an ashing process. This plasma processing apparatus is provided with a matching circuit 2A which is disposed between a radiofrequency generator 1 and a plasma excitation electrode (cathode) 4. The matching circuit 2A matches the impedance between the radiofrequency generator 1 and the excitation electrode 4.
Radiofrequency power from the radiofrequency generator 1 is fed to the plasma excitation electrode 4 via the matching circuit 2A and a feed plate 3. The matching circuit 2A is accommodated in a matching box 2 which is a housing composed of a conductive material. The plasma excitation electrode 4 and the feed plate 3 are covered by a conductive chassis 21.
The plasma excitation electrode 4 is provided with projections 4a at the bottom face thereof. A shower plate 5 having many holes 7 provided under the plasma excitation electrode 4 is in contact with the projection 4a. The plasma excitation electrode 4 and the shower plate 5 define a space 6. A gas feeding tube 17 comprising a conductor is connected to the space 6. The gas feeding tube 17 is provided with an insulator 17a at the middle thereof so as to insulate the plasma excitation electrode 4 and the gas source.
Gas from the gas feeding tube 17 is fed into a chamber space 60 composed of a chamber wall 10, via the holes 7 in the shower plate 5. An insulator 9 insulates the plasma excitation electrode 4 from the chamber wall 10. The exhaust system is not depicted in the drawing.
A susceptor electrode (wafer susceptor) 8 which holds a substrate 16 and functions as another plasma excitation electrode is provided in the chamber space 60. The wafer susceptor 8 is provided with a susceptor shield 12 thereunder.
The susceptor shield 12 comprises a shield supporting plate 12A for sustaining the susceptor electrode 8 and a cylindrical support 12B extending downward from the center of the shield supporting plate 12A. The cylindrical support 12B extends through a chamber bottom 10A, and the lower portion of the cylindrical support 12B and the chamber bottom 10A are hermetically sealed with a bellows 11.
The shaft 13 and the susceptor electrode 8 are electrically isolated from the susceptor shield 12 by a gap between the susceptor shield 12 and the susceptor electrode 8 and by insulators 12C provided around the shaft 13. The insulators 12C also maintain high vacuum in the chamber space 60. The susceptor electrode 8 and the susceptor shield 12 can be moved vertically by the bellows 11 to control the distance between the two electrodes 4 and 8.
The susceptor electrode 8 is connected to a second radiofrequency generator 15 via the shaft 13 and a matching circuit accommodated in a matching box 14. The chamber wall 10 and the susceptor shield 12 have the same DC potential.
FIG. 33 illustrates another example of conventional plasma processing apparatuses. Unlike the plasma processing apparatus shown in FIG. 32, the plasma processing apparatus shown in FIG. 33 is of a single-frequency excitation type. In detail, a radiofrequency power is supplied only to a cathode 4, a susceptor electrode 8 being grounded. Moreover, the matching box 14 and the radiofrequency generator 15 shown in FIG. 32 are not provided. The susceptor electrode 8 and a chamber wall 10 have the same DC potential.
In these conventional plasma processing apparatuses, power with a frequency of approximately 13.56 MHz is generally supplied to generate a plasma between the electrodes 4 and 8. A plasma process such as a plasma-enhanced CVD process, a sputtering process, a dry etching process, or an ashing process is then performed using the plasma.
The validation and evaluation of operation of the above-described plasma processing apparatuses have been performed by actual layer deposition and evaluation of the characteristics of the deposited layer, as follows.
Procedure (1): Deposition rate and planar uniformity
Step 1: Depositing a required layer on a 6-inch substrate by a plasma-enhanced CVD process.
Step 2: Patterning a resist layer by photolithography.
Step 3: Dry-etching the layer.
Step 4: Removing the resist layer by ashing.
Step 5: Measuring the surface roughness using a contact displacement meter to determine the layer thickness.
Step 6: Calculating the deposition rate from the deposition time and the layer thickness.
Step 7: Measuring the planar uniformity at 16 points on the substrate surface.
Procedure (2): BHF etching rate
A resist mask is patterned as in Steps 1 and 2 in Procedure (1).
Step 3: Immersing the substrate in a buffered hydrofluoric acid (BHF) solution for one minute to etch the layer.
Step 4: Rinsing the substrate with deionized water, drying the substrate, and removing the resist mask with a mixture of sulfuric acid and hydrogen peroxide (H2SO4+H2O2).
Step 5: Measuring the roughness as in Step 5 in Procedure (1) to determine the layer thickness after the etching.
Step 6: Calculating the etching rate from the immersion time and the reduced layer thickness.
Procedure (3): Isolation voltage
Step 1: Depositing a conductive layer on a glass substrate by a sputtering method and patterning the conductive layer to form a lower electrode.
Step 2: Depositing an insulating layer by a plasma-enhanced CVD process.
Step 3: Forming an upper electrode as in Step 1.
Step 4: Forming a contact hole for the lower electrode.
Step 5: Measuring the current-voltage characteristics (I-V characteristics) of the insulating layer by probing the upper and lower electrodes while varying the voltage up to approximately 200 V.
Step 6: Defining the isolation voltage as a voltage V at 100 pA corresponding 1 xcexcA/cm2 in a 100 xcexcm square electrode.
The plasma processing apparatus has been required to achieve a higher plasma processing rate (a deposition rate or a processing rate), improved productivity, and improved planar uniformity in the plasma processing of substrates to be treated (a uniform distribution of the layer thickness and a uniform process in the planar direction). With an increased size of substrates in recent years, the requirement for planar uniformity is becoming more severe. Moreover, with an increased size of the substrate, the power required is also increased to the order of kilowatts, thus increasing the power consumption. As the capacity of the power supply increases, both costs for developing the power supply and for operating the apparatus consuming much power increase. Accordingly, it is desirable to reduce the operation costs.
Furthermore, an increase in power consumption leads to an increase in emission of carbon dioxide which places a burden on the environment. Since the power consumption is increased by the combination of an increase in the size of substrates and a low power consumption efficiency, there is a growing demand to reduce the carbon dioxide emission.
The plasma density generated in the plasma space can be improved by shifting the plasma excitation frequency to a higher side. For example, a frequency of 30 MHz or more in the VHF band can be used instead of the conventional 13.56 MHz. Thus, one possible way to improve the deposition rate in a deposition apparatus such as a plasma-enhanced CVD apparatus is to employ a higher plasma excitation frequency.
Another type of plasma processing apparatus has a plurality of plasma chambers. Such a plasma processing apparatus is also required to achieve a higher plasma processing rate (a deposition rate or a processing rate), improved productivity, and improved planar uniformity in the plasma processing of the substrates (a uniform distribution of the layer thickness and a uniform process in the planar direction), when the substrates are treated in different plasma chambers.
Moreover, these plasma chambers of the plasma processing apparatus are required to achieve substantially the same plasma processing results using the same process recipe specifying external parameters such as the flow rate and pressure of the charged gasses, the supplied power, and the treatment time.
A request at the time of installation or maintenance of the plasma processing apparatus is to reduce time for adjusting the apparatus to eliminate processing variations among the individual plasma chambers, so that substantially the same process results can be achieved using the same process recipe. Reduction in the cost for such adjustment is also required.
A plasma processing system equipped with a plurality of the above-described plasma processing apparatuses is also required to eliminate plasma processing variations among individual plasma chambers of these plasma processing apparatuses.
The above conventional plasma processing apparatuses are designed to use a power having a frequency of approximately 13.56 MHz and is not suited for higher frequencies. In detail, units to which the radiofrequency voltage is applied, i.e., plasma processing chambers are not designed in view of radiofrequency characteristics, such as impedance and resonance frequency characteristics. Thus, a loss current Ix which shunts to other components in the plasma chamber increases relative to a plasma current Ie supplied to the plasma space. Such a decrease in electrical power consumption in the plasma chamber results in a decrease in plasma density therein.
When a power having a frequency exceeding 13.56 MHz is supplied, the deposition rate is not improved, but rather decreased in some cases during the deposition process. Although the effective power consumed in the plasma space increases as the frequency increases, the power starts to decrease once the power reaches its peak value, eventually reaching a level at which glow-discharge no longer occur, thus rendering further increases in frequency meaningless.
In the plasma processing apparatuses and plasma processing systems, each having a plurality of plasma processing chambers, the radiofrequency characteristics of each plasma chamber are determined by the size and the shape thereof. Since each component constituting the plasma chamber has a variation in size due to machining tolerance which is inevitable in mechanical processing for the chamber production. In addition, each plasma chamber has assembling tolerance. Moreover, the plasma chamber includes portions in which sizes thereof are unmeasurable after assembling. Thus, there are no means for quantitatively determining whether or not the assembled chamber has designed radiofrequency characteristics and means for measuring difference in radiofrequency characteristics among plasma processing chambers.
As a result, the following problems arise.
The effective power consumed and the plasma density generated in the plasma space may not be equal between these plasma processing chambers. The same plasma processing results may not be obtained when the same process recipe is used for a plurality of plasma processing chambers.
Accordingly, in order to obtain the same plasma processing results, external parameters, such as a gas flow and a pressure, a supplied power, and a process time, must be compared with the process results according to Procedures (1) to (3) described above for each of the plasma chambers so as to determine the correlation between them. However, the amount of data is too enormous to completely perform the comparison.
When Procedures (1) to (3) described above are employed to validate and evaluate the operation of the plasma processing apparatus, it becomes necessary to actually operate the plasma processing apparatus and to examine the treated substrates at a different site by a plurality of inspection steps.
Since such an inspection requires several days to several weeks to yield evaluation results, it is desired that the time for performance inspection of a plasma processing apparatus be reduced in the development stage thereof.
Moreover, when Procedures (1) to (3) described above are employed to inspect the plasma processing apparatus or system having a plurality of plasma chambers, a time over months will be required for adjusting the plasma processing chambers in order to eliminate the difference in performance and the variation in processing among the plasma processing chambers and in order to achieve the same processing results using the same process recipe. The time required for such adjustment needs to be reduced. Also, the cost of substrates for inspection, the cost of processing the substrates for inspection, the labor cost for engineers involved with the adjustment and so forth are significantly high.
In view of the above problems, the present invention aims to achieve the following objects.
(1) To improve power consumption in the plasma space in order to achieve a processing rate and to obtain layer characteristics which are substantially equal to those in conventional apparatuses by reduced power supply compared with conventional apparatuses.
(2) To improve the plasma density in order to achieve improvements in plasma processing, that is, improving the planar uniformity of the plasma processing of the treated substrate (improving the thickness uniformity processing uniformity in the planar direction), and improving characteristics, such as isolation voltage, of a layer deposited by a plasma-enhanced CVD or sputtering system.
(3) To improve the processing rate (the deposition rate in a layer deposition system or the processing rate in a processing system) by shifting the plasma excitation frequency to the higher side.
(4) To obtain substantially the same radiofrequency characteristics, such as capacitance, impedance, and resonant frequency, for a plurality of plasma processing chambers.
(5) To obtain substantially the same process results from a plurality of plasma processing chambers using the same process recipe.
(6) To eliminate the determination of the process condition by the relationships between the external parameters and the process results based on Procedures (1) to (3) described above using enormous amounts of data on a plurality of plasma chambers.
(7) To reduce the time for adjustment which is performed to obtain the same process results from the same process recipe.
(8) To reduce operation and maintenance costs and to improve productivity.
(9) To provide a plasma processing apparatus and a plasma processing system which can readily maintain a normal operation state by a standard for performance validation of plasma processing chambers without actually treating substrates.
According to a first aspect of the present invention, a plasma processing apparatus comprises a plasma processing chamber having a plasma excitation electrode, a susceptor electrode, and a radiofrequency feeder, the plasma excitation electrode and the susceptor electrode generating a plasma in cooperation with each other; a radiofrequency generator for supplying a radiofrequency voltage to the plasma excitation electrode; and a matching circuit having an input terminal and an output terminal, the input terminal being connected to the radiofrequency generator and the output terminal being connected to an input end of the radiofrequency feeder so as to achieve impedance matching between the plasma processing chamber and the radiofrequency generator, wherein 26 times a plasma electrode capacitance Ce between the plasma excitation electrode and the susceptor electrode is greater than a loss capacitance CX between the plasma excitation electrode and ground potential positions which are DC-grounded.
Preferably, 7 times the plasma electrode capacitance Ce is greater than the loss capacitance CX. More preferably, 5 times the plasma electrode capacitance Ce is greater than the loss capacitance CX.
According to a second aspect of the present invention, a plasma processing apparatus comprises a plurality of plasma processing chamber units, each unit comprising a plasma processing chamber having a plasma excitation electrode, a susceptor electrode, and a radiofrequency feeder, the plasma excitation electrode and the susceptor electrode generating a plasma in cooperation with each other; a radiofrequency generator for supplying a radiofrequency voltage to the plasma excitation electrode; and a matching circuit having an input terminal and an output terminal, the input terminal being connected to the radiofrequency generator and the output terminal being connected to an input end of the radiofrequency feeder so as to achieve impedance matching between the plasma processing chamber and the radiofrequency generator, wherein a variation in plasma electrode capacitance Ce between the plasma excitation electrode and the susceptor electrode among the plurality of plasma processing chambers is set within a predetermined value, the variation being defined by (Cemaxxe2x88x92Cemin)/(Cemax+Cemin) wherein Cemax and Cemin are the maximum and the minimum, respectively, of the plasma electrode capacitance Ce, and a variation in loss capacitance CX between the plasma excitation electrode and ground potential positions which are DC-grounded among the plasma processing chambers is set within a predetermined value, the variation being defined by (CXmaxxe2x88x92CXmin)/(CXmax+CXmin) wherein CXmax and CXmin are the maximum and the minimum, respectively, of the loss capacitance CX.
Preferably, both the variation in the plasma electrode capacitance Ce and the variation in the loss capacitance CX are less than 0.1. More preferably, both the variation in the plasma electrode capacitance Ce and the variation in the loss capacitance CX are less than 0.03. Preferably, 26 times the plasma electrode capacitance Ce is greater than the loss capacitance CX.
In these aspects, the plasma excitation electrode and the susceptor electrode may be of a parallel plate type, the plasma excitation electrode constitutes a part of an upper component of the plasma processing chamber, and the loss capacitance CX is a capacitance which is measured at a measuring position corresponding to the output terminal of the matching circuit of the upper component.
In the above aspects, preferably, the plasma processing apparatus further comprises a measuring terminal provided in the vicinity of the measuring position for measuring radiofrequency characteristics of the plasma processing chamber, and a switch which electrically disconnects the measuring position from the measuring terminal and electrically connects the radiofrequency feeder to the radiofrequency generator when the plasma is excited and which electrically connects the measuring position to the measuring terminal and electrically disconnects the radiofrequency feeder from the radiofrequency generator when the radiofrequency characteristics of the plasma processing chamber are measured.
Since the measuring terminal is disconnected from the electrical path including the radiofrequency generator, the radiofrequency supplier, the matching circuit, the radiofrequency feeder, and the plasma excitation electrode in a measuring mode, the radiofrequency characteristics including capacitance can be readily measured by operating the switch without detaching an impedance measuring probe. Since the switch eliminates mechanical detachment of the components which lie in the unmeasured region, the radiofrequency characteristics of the plasma processing chamber or the upper component can be more precisely measured. Thus, the radiofrequency characteristics of a plurality of plasma chambers can be readily measured, and the difference in the radiofrequency characteristics between plasma processing chambers can be readily eliminated. In conventional methods, such installation and maintenance operations require long periods over months.
According to a third aspect of the present invention, a plasma processing system comprises a plurality of plasma processing apparatuses, each plasma processing apparatus comprising a plurality of plasma processing chambers, each plasma processing chamber comprising: a plasma processing chamber having a plasma excitation electrode, a susceptor electrode, and a radiofrequency feeder, the plasma excitation electrode and the susceptor electrode generating a plasma in cooperation with each other; a radiofrequency generator for supplying a radiofrequency voltage to the plasma excitation electrode; and a matching circuit having an input terminal and an output terminal, the input terminal being connected to the radiofrequency generator and the output terminal being connected to an input end of the radiofrequency feeder so as to achieve impedance matching between the plasma processing chamber and the radiofrequency generator, wherein a variation in plasma electrode capacitance Ce between the plasma excitation electrode and the susceptor electrode among the plurality of plasma processing chambers is set within a predetermined value, the variation being defined by (Cemaxxe2x88x92Cemin)/(Cemax+Cemin) wherein Cemax and Cemin are the maximum and the minimum, respectively, of the plasma electrode capacitance Ce, and a variation in loss capacitance CX between the plasma excitation electrode and ground potential positions which are DC-grounded among the plasma processing chambers is set within a predetermined value, the variation being defined by (CXmaxxe2x88x92CXmin)/(CXmax+CXmin) wherein CXmax and CXmin are the maximum and the minimum, respectively, of the loss capacitance CX.
In the third aspect, both the variation in the plasma electrode capacitance Ce and the variation in the loss capacitance CX are preferably less than 0.1 and more preferably less than 0.03. Preferably, 26 times the plasma electrode capacitance Ce is greater than the loss capacitance CX. More preferably, 7 times the plasma electrode capacitance Ce is greater than the loss capacitance CX. More preferably, 5 times the plasma electrode capacitance Ce is greater than the loss capacitance CX.
In this aspect, the plasma excitation electrode and the susceptor electrode may be of a parallel plate type, the plasma excitation electrode constitutes a part of an upper component of the plasma processing chamber, and the loss capacitance CX is a capacitance which is measured at a measuring position corresponding to the output terminal of the matching circuit of the upper component.
Preferably, the plasma processing system further comprises a measuring terminal provided in the vicinity of the measuring position for measuring radiofrequency characteristics of the plasma processing chamber, and a switch which electrically disconnects the measuring position from the measuring terminal and electrically connects the radiofrequency feeder to the radiofrequency generator when the plasma is excited and which electrically connects the measuring position to the measuring terminal and electrically disconnects the radiofrequency feeder from the radiofrequency generator when the radiofrequency characteristics of the plasma processing chamber are measured.
Preferably, the plasma processing system further comprises a radiofrequency-measuring meter which is detachably connected to the measuring terminal of each of the plurality of plasma processing chambers.
Since these plasma processing chambers have substantially the same radiofrequency characteristics, these plasma processing chambers consume substantially the same radiofrequency power in the plasma spaces. As a result, substantially the same results can be obtained by the same process recipe for these plasma processing chambers. When layers are deposited in these processing chambers, these layers will have substantially the same characteristics, e.g., the thickness, the isolation voltage, and the etching rate.
When the above variations are less than 0.1, the variation in layer thickness dan be controlled within xc2x15% under the same deposition conditions.
When the above variations are less than 0.03, the variation in layer thickness can be controlled within xc2x12% under the same deposition conditions.
Since the radiofrequency-measuring meter is detached from the measuring terminal in the measuring mode, the radiofrequency-measuring meter is not electrically affected during the plasma generation. Moreover, the radiofrequency characteristics of a plurality of plasma processing chambers can be measured using one radiofrequency-measuring meter.
Preferably, the radiofrequency characteristics between the measuring position and the radiofrequency-measuring meter are the same among the plurality of plasma processing chambers.
According to a fourth aspect of the present invention, a performance validation system for the plasma processing apparatus according to the first or second aspect or the plasma processing system according to the third aspect, comprises a customer terminal, an engineer terminal, and information providing means, wherein the customer terminal requests browsing of performance information to the information providing means via a public line, a maintenance engineer uploads the performance information to the information providing means through the engineer terminal, and the information providing means provides the performance information uploaded from the engineer terminal to the customer terminal upon the request from the customer terminal.
The customer can easily obtain the information for purchasing the plasma processing apparatus or system of the present invention and the information regarding the operations and maintenance of the apparatus or system in use.
Preferably, the performance information comprises the plasma electrode capacitance Ce. The performance information may be output as a catalog or specifications.
According to a fifth aspect of the present invention, in an inspection method for a plasma processing apparatus having a plasma processing chamber having a plasma excitation electrode, a susceptor electrode, and a radiofrequency feeder, the plasma excitation electrode and the susceptor electrode generating a plasma in cooperation with each other; a radiofrequency generator for supplying a radiofrequency voltage to the plasma excitation electrode; and a matching circuit having an input terminal and an output terminal, the input terminal being connected to the radiofrequency generator and the output terminal being connected to an input end of the radiofrequency feeder so as to achieve impedance matching between the plasma processing chamber and the radiofrequency generator, the method comprises setting the plasma electrode capacitance Ce between the plasma excitation electrode and the susceptor electrode and the loss capacitance CX between the plasma excitation electrode and ground potential positions which are DC-grounded such that 26 times the plasma electrode capacitance Ce is greater than the loss capacitance CX.
Preferably, 7 times the plasma electrode capacitance Ce is greater than the loss capacitance CX. More preferably, 5 times the plasma electrode capacitance Ce is greater than the loss capacitance CX.
The plasma excitation electrode and the susceptor electrode may be of a parallel plate type, the plasma excitation electrode constitutes a part of an upper component of the plasma processing chamber, and the loss capacitance CX is a capacitance which is measured at a measuring position corresponding to the output terminal of the matching circuit of the upper component.
According to a sixth aspect of the present invention, in an inspection method for a plasma processing apparatus having a plurality of plasma processing chamber units, each unit comprising: a plasma processing chamber having a plasma excitation electrode, a susceptor electrode, and a radiofrequency feeder, the plasma excitation electrode and the susceptor electrode generating a plasma in cooperation with each other; a radiofrequency generator for supplying a radiofrequency voltage to the plasma excitation electrode; and a matching circuit having an input terminal and an output terminal, the input terminal being connected to the radiofrequency generator and the output terminal being connected to an input end of the radiofrequency feeder so as to achieve impedance matching between the plasma processing chamber and the radiofrequency generator, the method comprises setting a variation in plasma electrode capacitance Ce between the plasma excitation electrode and the susceptor electrode among the plurality of plasma processing chambers at a predetermined value wherein the variation is defined by (Cemaxxe2x88x92Cemin)/(Cemax+Cemin) wherein Cemax and Cemin are the maximum and the minimum, respectively, of the plasma electrode capacitance Ce and a variation in loss capacitance CX between the plasma excitation electrode and ground potential positions which are DC-grounded among the plasma processing chambers at a predetermined value wherein the variation is defined by (CXmaxxe2x88x92CXmin)/(CXmax+CXmin) wherein CXmax and CXmin are the maximum and the minimum, respectively, of the loss capacitance CX.
Both the variation in the plasma electrode capacitance Ce and the variation in the loss capacitance CX are set such that they are preferably less than 0.1 and more preferably less than 0.03.
Preferably, 26 times the plasma electrode capacitance Ce is greater than the loss capacitance CX.
The plasma excitation electrode and the susceptor electrode may be of a parallel plate type, the plasma excitation electrode constitutes a part of an upper component of the plasma processing chamber, and the loss capacitance CX is a capacitance which is measured at a measuring position corresponding to the output terminal of the matching circuit of the upper component.
According to a seventh embodiment, in an inspection method for a plasma processing system having a plurality of plasma processing apparatuses, each plasma processing apparatus having a plurality of plasma processing chambers, each plasma processing chamber comprising: a plasma processing chamber having a plasma excitation electrode, a susceptor electrode, and a radiofrequency feeder, the plasma excitation electrode and the susceptor electrode generating a plasma in cooperation with each other; a radiofrequency generator for supplying a radiofrequency voltage to the plasma excitation electrode; and a matching circuit having an input terminal and an output terminal, the input terminal being connected to the radiofrequency generator and the output terminal being connected to an input end of the radiofrequency feeder so as to achieve impedance matching between the plasma processing chamber and the radiofrequency generator, the method comprises setting a variation in plasma electrode capacitance Ce between the plasma excitation electrode and the susceptor electrode among the plurality of plasma processing chambers at a predetermined value wherein the variation is defined by (Cemaxxe2x88x92Cemin)/(Cemax+Cemin) wherein Cemax and Cemin are the maximum and the minimum, respectively, of the plasma electrode capacitance Ce and a variation in loss capacitance CX between the plasma excitation electrode and ground potential positions which are DC-grounded among the plasma processing chambers at a predetermined value wherein the variation is defined by (CXmaxxe2x88x92CXmin)/(CXmax+CXmin) wherein CXmax and CXmin are the maximum and the minimum, respectively, of the loss capacitance CX.
Both the variation in the plasma electrode capacitance Ce and the variation in the loss capacitance CX are set such that they are preferably less than 0.1 and more preferably less than 0.03.
Preferably, 26 times the plasma electrode capacitance Ce is greater than the loss capacitance CX. More preferably, 7 times the plasma electrode capacitance Ce is greater than the loss capacitance CX. Most preferably, 5 times the plasma electrode capacitance Ce is greater than the loss capacitance CX.
The plasma excitation electrode and the susceptor electrode may be of a parallel plate type, the plasma excitation electrode constitutes a part of an upper component of the plasma processing chamber, and the loss capacitance CX is a capacitance which is measured at a measuring position corresponding to the output terminal of the matching circuit of the upper component.
In the present invention, 26 times the plasma electrode capacitance Ce is greater than the loss capacitance CX. Since the shunt component of the current from the radiofrequency generator is reduced, the input power can be effectively consumed in the plasma chamber. Thus, the effective power consumption in the plasma space is achieved compared with conventional plasma processing apparatuses when the same frequency is supplied. In a layer deposition process, the deposition rate will be improved.
Since the plasma electrode capacitance Ce and the loss capacitance CX are radiofrequency characteristics mainly depending on the mechanical structure, thus the individual plasma processing chambers have different values. By controlling the plasma electrode capacitance Ce and the loss capacitance CX to the above-described conditions, the overall radiofrequency characteristics of the plasma chambers can be optimized, achieving stable plasma generation. Consequently, the plasma processing apparatus exhibits improved operation stability.
When 7 times the plasma electrode capacitance Ce is greater than the loss capacitance CX, the shunt components flowing in the ground potential positions can be reduced. Thus, the power can be effectively fed into the plasma space, and the effective power consumption in the plasma space is achieved compared with conventional plasma processing apparatuses when the same frequency is supplied. In a layer deposition process, the deposition rate will be improved. In addition, the resulting layer exhibits excellent characteristics, such as isolation voltage, etching resistance to etching solutions, and density or hardness of the deposited layer. Since the radiofrequency current is concentrated between the two electrodes, the radiofrequency power is more effectively consumed in the plasma space. Thus, the resulting layer has planar uniformity, namely, reduced variations in thickness and isolation voltage in the planar direction.
When 5 times the plasma electrode capacitance Ce is greater than the loss capacitance CX, the deposition rate can be further increased and the planar uniformity of the thickness and the isolation voltage can be more readily achieved by reduced input power. Thus, the operational costs can be reduced.
Accordingly, in the present invention, the capacitance characteristics are used in the installation and maintenance of the plasma processing apparatus and the plasma processing system. The capacitance is more readily measured using an inexpensive meter, compared with a measurement of the radiofrequency characteristics such as impedance.